1. Field of the Invention
The present invention relates generally to the manufacture of walk-in bathtubs and associated tub doors, more specifically to a method for manufacturing a walk-in tub side door preferably formed of acrylic.
2. Description of Related Art
Walk-in bathtubs comprise high tub walls with a high built-in seat and a side door, allowing the user to walk into the tub from the side and sit down without having to climb down into a low bath tub. FIG. 1 shows a typical example of a walk-in bathtub in accordance with the prior art. Walk-in tubs are particularly suited for individuals who have physical limitations that make it difficult or dangerous to climb into and out of a regular, low bathtub or to stand up in a shower for extended periods of time. Such limitations might include physical disabilities or simply the reduced strength, balance and range of motion that typically occur with advancing age. Walk-in tubs are not only easier to enter and exit than conventional bathtubs, they also reduce the risk of a slip and fall in comparison with conventional tubs and showers.
In addition to safety, the ease of entering the tub via the side walk-in door also provides users with independence, allowing them to bathe without the assistance of another person when getting into and out of the tub.
Acrylic is the preferred material for conventional bathtub manufacturers. Acrylic is germ- and stain-resistant, has good heat-retaining qualities and is durable. Because acrylic is non-porous, mildew and algae cannot stick to it. It wipes clean with common household non-abrasive cleaners. Even grease, oil, hair dye and cosmetics that would stain other materials can be easily removed with rubbing alcohol.
However, because of their depth, walk-in bathtubs are typically made from gel-coated fiberglass, which does not offer the advantages of acrylic materials in terms of heat retention, stain resistance and strength. The reason for using fiberglass in manufacturing walk-in tubs lies in the technical difficulties encountered when forming the deep basin of the tub with a single sheet of acrylic. With seat heights approaching seventeen inches above the tub floor, acrylic has a tendency to tear during the vacuum forming process or become excessively thin at the bottom, compromising its ability to hold the requisite water weight.
Walk-in tub doors are critical to a positive walk-in tub experience. Most such doors open inwardly so that they are pressure sealed by the weight of water against the door when the door is filled, although various latch mechanisms are also provided. The ease with which such doors operate varies with their design, hinge mechanism and fit to the opening in the walk-in tub having a threshold area over which a user enters the tub. A smooth and sealingly engaged fit to the walk-in tub threshold as well as a door that is economical to manufacture are desirable in the art.
U.S. Pat. No. 7,788,783 teaches a method of manufacturing walk-in tubs and associated doors. The walk-in tub door is manufactured from two main pieces. A threshold piece is first vacuum formed and trimmed to fit a door opening in the side of a tub. A flat panel is then formed so that a peripheral edge of the flat panel mates with the peripheral edge of the trimmed threshold piece. The flat panel is then bonded to the threshold piece to form the tub door. A tub door is also described in U.S. Pat. No. 7,299,509 having a frame and extruded two-piece construction and also having two tracks for a gasket and hinge, respectively.
U.S. Patent Publication No. 2010/0263119 A1 teaches an improved hinge for opening and closing a walk-in bathtub door having a double axis hinge allowing the door to open in a way that provides more clearance than standard prior art one-axis hinged doors.
A need still exists for an improved method of forming a walk-in bathtub door that is economical and provides a smooth appearance and a reinforced structure.